Well-known for their ability to build dams, beavers live near ponds and lakes in the forested areas of the continental United States, Canada, and Europe. Many of these areas are known for their harsh winters when the temperatures not only drop considerably but the bodies of water freeze. What happens to the beavers then? Do they migrate or hibernate in winter?
Do Beavers Hibernate?
Beavers do not hibernate, nor do they migrate in winter. These semi-aquatic mammals are well adapted for living in cold climates and spend the winters protected from cold in their lodges. To survive harsh weather, beavers store food in underwater caches and reduce their activity to preserve energy.
If you live near wetlands, you may have seen beavers in the wild. In winter, when the temperatures drop and the pond starts to freeze, beavers retreat into their lodges. From the outside, it looks like they hibernate underwater. However, like other rodent species, beavers remain active throughout the year. In milder winters when the pond is not frozen, you might even spot them foraging through the forest.
Mountain beavers, who also live in North America but are unrelated to beavers, also remain active throughout the year and don’t hibernate.
Beavers don’t go into torpor because their bodies are not built to withstand large periods without sustenance.
Due to the architecture of their lodges, beavers can’t get out when the water is frozen. That’s why they stash twigs and branches in underwater caches to have enough food for the winter. Inside the dens, the rodents remain active and mate.
Beavers mate during the colder months so that the kits are born during the warm months of spring and summer. In this way, the young get big and strong enough to survive the next winter.
How Do Beavers Prepare For Winter?
Beavers don’t hibernate, but they do adapt to the environment and prepare for winter in several ways. The two most important aspects for survival are building dams and dens and food caching.
As you can imagine, beaver lodges provide the rodents with shelter – during winter but also throughout the rest of the year. They keep the beavers warm but also serve another role, keeping the predators out.
To stay away from predators, beavers generally build their lodges in the middle of the pond or lake. These lodges consist of a base that goes from the bottom of the pond all the way up above the water level and makes up the lodge floor. Above it, beavers build a domed roof. The rodents wove twigs and branches to build the floor and roof, then secure the structure with mud.
The mud not only helps keep the warmth inside in freezing weather, but it also gets very hard in the low temperatures. Thus, it prevents wolves, wolverines, and even bears from breaking the lodge and feasting on the beavers.
Lodges generally have two entrances, one that serves as the main entrance into the den and another that provides access to the food cache.
The dams are also essential for survival, preventing the water levels from dropping too low. Low water levels that go under the lodge entrance are dangerous during winter because the ice can restrict the access to the food cache on the bottom of the pond.
When living near a river or larger lake, beavers may also dig dens directly into the river bank or lake shore. In these cases, the dam creates an artificial pond where the rodents can live undisturbed.
These territorial mammals start building their dams and lodges as soon as they establish themselves in a territory. These structures are solid enough to hold up for several years with no or minimal repairs.
In addition to building lodges for shelter and dams to keep the water levels high, beavers also prepare for the winter by stashing food in caches on the bottom of the pond.
Food caching starts in the fall, when all family members join forces to cut down trees and gather branches and twigs. Beavers then transport the twigs and branches to the lodge and take them to the bottom of the pond, where they stick the thickest side of the branch into the mud.
From this base, the rodents start to wove the food cache, which often becomes high enough to go above water level.
Beavers access the food cache through a tunnel that opens inside the central chamber of the den. After the pond freezes, the beavers access the food cache through the tunnel, bringing food inside the lodge. Generally, beavers start to consume the greener twigs, any leaves, and existent water vegetation.
Then, they continue consuming the bark and cambium from the thicker branches, discarding their hardwood cores.
How Do Beavers Survive In The Cold?
In addition to dams, lodges, and food caches, beavers have a few other tricks to survive in the cold. One of their greatest allies is the thick, waterproof coat. The other is the internal layout of the lodge.
As semi-aquatic mammals, beavers have two layers of fur. The underfur, which is the layer closer to the beaver’s skin, consists of short, fluffy hair that traps the warmth against the rodent’s skin. The outer layer is coarser and long, acting as a shield that keeps water out.
Beavers also have glands near the base of the tail that secretes oil which the rodent then spreads throughout the fur. This oil creates a sort of impermeable membrane, preventing the cold water from soaking into the underfur.
Dual Chamber Lodges
Besides the coats, the structure of the lodge or den also helps trap warmth.
Beaver lodges consist of two separate rooms. The entrance and food cache tunnels open up into a central feeding room. Another chamber with an entrance from the central room serves as sleeping and nesting quarters. Here, the beavers sleep together, mate, and give birth to their young.
The construction of the lodge and the fact that the entire beaver family sleeps in the same chamber help preserve heat. An airway through the top of the lodge ensures airflow, and in the winter, you may be able to observe the steam generated by the beaver’s warm bodies escaping from it.
To preserve energy and increase their chances of survival, beavers also reduce their activity in winter and spend most of their time sleeping.
What Do Beavers Do When The Lake Freezes?
We already established that beavers can’t leave their lodges when the lake is frozen. However, they still have plenty of things to do when they’re not eating. While they mostly spend their time sleeping, beavers use this period for breeding.
Beavers are a monogamous species. The partners mate during the colder months, usually between January and March in the northern areas or between November and December in the warmer climates. They give birth to a litter each year, after a gestation period of about three months.
Kits are born from April to June, fully furred and with their eyes open. They are ready to take their first swim within 24 hours after being born and start diving out of the lodge and exploring the surrounding area when they are only several days old.
Babies have plenty of time to grow during summer and fall, when they are big enough to start helping their parents to reinforce the dam and lodge and to gather food. In winter, the entire family retreats to the lodge, where the older kits help their parents take care of the young.
When the new litter is born in the next spring, the older kits (about two years of age) leave their families and establish in new territories where they will start their own families.
What Is The Beaver Moon?
The beaver moon is a term referring to the full moon in November. This full moon is named after the beaver because, in most parts of North America and Europe, this is the month when the beavers have stashed sufficient supplies for the winter and start retreating into their lodges.
Because beavers are still fairly active during this month, this is when hunters used to set their traps and catch the rodents either for their meat or for their furs.
Beavers are territorial animals. They don’t migrate in winter, and they don’t hibernate either. During the cold months, the entire beaver family retreats into the lodge, where it spends time sleeping, mating, caring for the young, and feeding on the food stashed in underwater caches throughout the fall.
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